The present disclosure relates to a touchscreen device and a method of sensing touches.
A touchscreen device, such as a touchscreen and a touch pad, is a data input device attached to a display device to provide an intuitive user interface, and has recently been widely used in various electronic devices such as cellular phones, personal digital assistants (PDA) and navigation devices. Particularly, demand for smartphones has recently increased, touchscreens have been increasingly employed therein as devices providing users with various data input methods in a limited form factor.
Touchscreens used in portable devices may be mainly divided into resistive type touchscreens and capacitive type touchscreens, depending on the manner in which a touch is sensed therein. Among these, capacitive type touchscreens have advantages of a relatively long lifespan and ease of implementation of various data input schemes allowing for a variety of gestures to be used therefor, and thus have been increasingly employed. to The implementation of a multi-touch interface is especially easy with capacitive type touchscreens, as compared to resistive type touchscreen, and thus capacitive type touchscreens are widely used in smartphones and the like.
The capacitive type touchscreen includes a plurality of electrodes having a predetermined pattern and the electrodes define a plurality of nodes in which changes in capacitance are generated by touches. In the plurality of nodes arranged on a two-dimensional plane, changes in self-capacitance or in mutual-capacitance are generated by a touch, and coordinates of the touch may be calculated by applying, for example, a weighted average calculation method to the changes in capacitance generated in the plurality of nodes.
Recently, touchscreen devices have been employed in laptop computers, TVs and the like, devices having large screens, in addition to small mobile devices. As the size of the touchscreen devices is increased, the number and size of electrodes therein are also increased. Accordingly, when driving signals are sequentially applied to a plurality of electrodes, driving time is increased, proportionally to the increased number of electrodes, and capacitance is increased, proportionally to the increased size of the electrodes, so that the time for charging voltage, i.e., the driving time is increased.